Ultraviolet light emitting element and light emitting element package including the same

ABSTRACT

An embodiment discloses an ultraviolet light emitting element including: a light emitting structure including a first conductive semiconductor layer, a second conductive semiconductor layer, an active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer, and an etched region in which the first conductive semiconductor layer is exposed; a first insulating layer disposed on the light emitting structure and including a first hole which exposes a portion of the etched region; a first electrode electrically connected to the first conductive semiconductor layer; and a second electrode electrically connected to the second conductive semiconductor layer, wherein the light emitting structure includes an intermediate layer regrown on the first conductive semiconductor layer exposed in the first hole, the first electrode is disposed on the intermediate layer, the etched region includes a first etched region disposed at an inner side and a second etched region disposed at an outer side based on an outer side surface of the first electrode, and a ratio of an area of the first etched region and an area of the intermediate layer is 1:0.3 to 1:0.7, and a light emitting element package including the same.

RELATED APPLICATIONS

This application claims the benefit of priority of Korean PatentApplication Nos. 10-2020-0123099 filed on Sep. 23, 2020 and10-2020-0113153 filed on Sep. 4, 2020, the contents of which areincorporated herein by reference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

Embodiments relate to an ultraviolet light emitting element and a lightemitting element package including the same.

A light emitting diode (LED) is an important solid-state element whichconverts electrical energy into light, and generally includes an activelayer of a semiconductor material interposed between two opposite dopedlayers. When a bias is applied to both ends of two doped layers, holesand electrons are injected into the active layer and then recombined togenerate light. The light generated in an active region is emitted inall directions and escapes out of a semiconductor chip through allexposed surfaces. Packaging of the LED is generally used to direct theescaping light in a desired output emission type.

Recently, since application fields expand and demand for high-power UVLED products increases, a lot of research and development is beingconducted to enhance optical output.

Recently, an ultraviolet (UV) LED in which interest increases as demandsfor water treatment and sterilization products sharply increase can bemanufactured by growing a buffer layer, an n-type semiconductor layer,an active layer, and a p-type semiconductor layer on a sapphiresubstrate or the like.

However, in the UV LED, since an AlGaN layer having a high aluminumcomposition is used, there is a problem in that an operating voltageincreases due to difficulty in ohmic contact between the n-typesemiconductor, the p-type semiconductor, and a metal electrode and thereis a problem in that light extraction efficiency is degraded as themetal electrode does not sufficiently reflect the ultraviolet light.

SUMMARY OF THE INVENTION

An embodiment is directed to providing a light emitting element of whichan operating voltage is lowered and a light emitting element packageincluding the same.

Further, an embodiment is directed to providing a light emitting elementof which optical output is improved and a light emitting element packageincluding the same.

In addition, an embodiment is directed to providing a light emittingelement which is resistant to corrosion and a light emitting elementpackage including the same.

In addition, an embodiment is directed to providing a light emittingelement capable of blocking propagation of cracks and a light emittingelement package including the same.

Problems to be solved by the embodiments are not limited to theabove-described problems, and purposes and effects understood from thesolutions and embodiments which will be described below are alsoincluded.

According to an aspect of the present disclosure, there is provided anultraviolet light emitting element including: a light emitting structureincluding a first conductive semiconductor layer, a second conductivesemiconductor layer, an active layer disposed between the firstconductive semiconductor layer and the second conductive semiconductorlayer, and an etched region in which the first conductive semiconductorlayer is exposed; a first insulating layer disposed on the lightemitting structure and including a first hole which exposes a portion ofthe etched region; a first electrode electrically connected to the firstconductive semiconductor layer; and a second electrode electricallyconnected to the second conductive semiconductor layer, wherein thelight emitting structure includes an intermediate layer regrown on thefirst conductive semiconductor layer exposed in the first hole, thefirst electrode is disposed on the intermediate layer, the etched regionincludes a first etched region disposed at an inner side and a secondetched region disposed at an outer side based on an outer side surfaceof the first electrode, and a ratio of an area of the first etchedregion and an area of the intermediate layer is 1:0.3 to 1:0.7.

A thickness of the intermediate layer may be smaller than a thickness ofthe first insulating layer.

A ratio of the thickness of the first insulating layer and the thicknessof the intermediate layer is 1:0.03 to 1:0.5.

The first insulating layer may include a first extending portionextending to an upper portion of the intermediate layer.

The first electrode may include a second extending portion extending toan upper portion of the first insulating layer, and a width of thesecond extending portion may be 5 μm to 15 μm.

First intermediate layers and second intermediate layers havingdifferent aluminum compositions may be stacked multiple times in theintermediate layer, and the aluminum composition of each of the firstintermediate layers may be higher than the aluminum composition of eachof the second intermediate layers.

The first conductive semiconductor layer may include a first subsemiconductor layer, a second sub semiconductor layer disposed on thefirst sub semiconductor layer, a third sub semiconductor layer disposedon the second sub semiconductor layer, and a fourth sub semiconductorlayer disposed on the third sub semiconductor layer, an aluminumcomposition of the second sub semiconductor layer may be lower thanaluminum compositions of the first sub semiconductor layer and thefourth sub semiconductor layer, an aluminum composition of the third subsemiconductor layer may be lower than the aluminum composition of thesecond sub semiconductor layer, and the intermediate layer may bedisposed on the third sub semiconductor layer.

An aluminum composition of the intermediate layer may be lower than thealuminum composition of the third sub semiconductor layer.

The light emitting structure may include a plurality of light emittingregions extending in a first direction and spaced apart from each otherin a second direction perpendicular to the first direction, theintermediate layer may include a plurality of finger portions disposedbetween the plurality of light emitting regions and each having a firstend and a second end and an edge portion extending along an edge of theetched region, and the edge portion may be connected to the first endsand the second ends of the plurality of finger portions.

A width of the first end may be greater than a width of the second endin each of the plurality of finger portions.

The first electrode may include a plurality of finger electrodesdisposed between the plurality of light emitting regions and each havinga first end and a second end and an edge electrode extending along anedge of the etched region, the edge electrode may be connected to thefirst ends and the second ends of the plurality of finger electrodes,and a width of the first end may be greater than a width of the secondend in each of the plurality of finger electrodes.

The ultraviolet light emitting element may include a second insulatinglayer disposed on the first electrode and the second electrode, andincluding a first opening which exposes the first electrode and a secondopening which exposes the second electrode, a first pad disposed on thesecond insulating layer and electrically connected to the firstelectrode through the first opening, and a second pad disposed on thesecond insulating layer and electrically connected to the secondelectrode through the second opening.

The first opening may be disposed on the first ends of the fingerportions, and the second opening may be disposed on the secondelectrode.

Each of the plurality of light emitting regions may include a first endand a second end, the first end of each of the plurality of lightemitting regions may include curved portions curved in directionsreceding from each other, and the first pad may overlap the curvedportions of the plurality of light emitting regions.

According to another aspect of the present disclosure, there is providedan ultraviolet light emitting element including: a substrate; a bufferlayer disposed on the substrate; a light emitting structure including afirst conductive semiconductor layer disposed on the buffer layer, anactive layer disposed on the first conductive semiconductor layer, asecond conductive semiconductor layer disposed on the active layer, anda first etched region in which the first conductive semiconductor layeris exposed; a first electrode disposed on the first conductivesemiconductor layer exposed to the first etched region; a secondelectrode disposed on the second conductive semiconductor layer; and aninsulating layer disposed on the first electrode and the secondelectrode, wherein a side surface of the insulating layer includes aplurality of protrusions protruding to the outside.

The side surface of the insulating layer may include the plurality ofprotrusions and a plurality of straight portions disposed between theplurality of protrusions.

The light emitting structure may include a second etched region formedat the outside of the first etched region to expose the buffer layer,and the protrusions of the insulating layer may be formed in the secondetched region.

An area of the second etched region may be larger than an area of thefirst etched region.

A depth of the second etched region may be greater than a depth of thefirst etched region.

A height of a side surface of the first conductive semiconductor layerexposed by the second etched region may be larger than a height of aside surface of the buffer layer exposed by the second etched region.

The second etched region may include a cover region in which theinsulating layer is disposed, and a ratio of an area of the cover regionand an area of the first etched region may be 1:3.5 to 1:6.0.

An inclination angle of the side surface of the first conductivesemiconductor layer exposed to the second etched region may be largerthan an inclination angle of the side surface of the buffer layerexposed to the second etched region.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The above and other objects, features and advantages of the presentdisclosure will become more apparent to those of ordinary skill in theart by describing in detail exemplary embodiments thereof with referenceto the accompanying drawings, in which:

FIG. 1 is a conceptual diagram of a light emitting element according toone embodiment of the present disclosure;

FIG. 2 is an enlarged view of portion A in FIG. 1 ;

FIG. 3 is a view illustrating a stacking structure of an intermediatelayer;

FIG. 4 is a modified example of FIG. 2 ;

FIG. 5 is a plan view illustrating the intermediate layer;

FIG. 6 is a plan view illustrating a first electrode;

FIG. 7 is a plan view of the light emitting element according to oneembodiment of the present disclosure;

FIGS. 8A and 8B are a plan view and a cross-sectional view illustratinga state in which a light emitting region and an etched region are formedby mesa etching, respectively;

FIGS. 9A and 9B are a plan view and a cross-sectional view illustratinga state in which an intermediate layer is regrown on a first conductivesemiconductor layer, respectively;

FIGS. 10A and 10B are a plan view and a cross-sectional viewillustrating a state in which a first electrode is formed, respectively;

FIGS. 11A and 11B are a plan view and a cross-sectional viewillustrating a state in which a second electrode is formed,respectively;

FIGS. 12A and 12B are graphs for describing an effect of improving anelectrical characteristic (VF enhancement) and an optical characteristic(optical output enhancement) of a short wavelength ultraviolet lightemitting diode (LED) (a peak wavelength of 265 nm) according to oneembodiment of the present disclosure;

FIG. 13 is a conceptual diagram of a light emitting element according toanother embodiment of the present disclosure;

FIG. 14 is a view illustrating inclination angles of a buffer layer anda first conductive semiconductor layer;

FIG. 15 is a cross-sectional view of the light emitting elementaccording to another embodiment of the present disclosure;

FIG. 16 is a portion of the plan view of the light emitting elementaccording to one embodiment of the present disclosure; and

FIGS. 17A, 17B, 17C, 17D and 17E are views illustrating various shapesof a side surface of an insulating layer.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The embodiments may be modified into other forms or some of theembodiments may be combined, and the scope of the present disclosure isnot limited to the embodiments which will be described below.

Although items described in a specific embodiment are not described inanother embodiment, the items may be understood as a description relatedto the other embodiment unless a description contrary to orcontradicting the items is in the other embodiment.

For example, when a characteristic of a component A is described in aspecific embodiment and a characteristic of a component B is describedin another embodiment, the characteristics of the components areunderstood to fall within the scope of the present disclosure unless acontrary or contradictory description is present even when an embodimentin which the component A and the component B are combined is not clearlydisclosed.

In the description of the embodiments, when one element is disclosed tobe formed “on or under” another element, the term “on or under” includesboth a case in which the two elements are in direct contact with eachother and a case in which at least one other element is disposed betweenthe two elements (indirect contact). Further, when the term “on orunder” is expressed, a meaning of not only an upward direction but alsoa downward direction with respect to one element may be included.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings so that those skilledin the art may easily carry out the embodiment of the presentdisclosure.

FIG. 1 is a conceptual diagram of a light emitting element according toone embodiment of the present disclosure, FIG. 2 is an enlarged view ofportion A in FIG. 1 , FIG. 3 is a view illustrating a stacking structureof an intermediate layer, and FIG. 4 is a modified example of FIG. 2 .

Referring to FIGS. 1 and 2 , a light emitting structure according to theembodiment of the present disclosure may emit light in an ultravioletwavelength band. For example, the light emitting structure may emitlight in a near ultraviolet wavelength band (ultraviolet (UV)-A), mayemit light in a far ultraviolet wavelength band (UV-B), and may emitlight in a deep ultraviolet wavelength band (UV-C).

For example, the light in the near ultraviolet wavelength band (UV-A)may have a peak wavelength in a range from 320 nm to 420 nm, the lightin the far ultraviolet wavelength band (UV-B) may have a peak wavelengthin a range from 280 nm to 320 nm, and the light in the deep ultravioletwavelength band (UV-C) may have a peak wavelength in a range from 100 nmto 280 nm.

When the light emitting structure (120, 130, and 140) emits light in anultraviolet wavelength band, each layer of the light emitting structuremay include a material having a composition formula ofIn_(x1)Al_(y1)Ga_(1-x1-y1)N (0≤x1≤1, 0<y1≤1, and 0≤x1+y1≤1) includingaluminum. Here, an aluminum composition may be represented as a ratio ofa total atomic weight including an atomic weight of In, an atomic weightof Ga, and an atomic weight of Al, and the atomic weight of Al. Forexample, when the aluminum composition is 40%, a Ga composition may be60%, that is, the composition formula may be Al_(0.4)Ga_(0.6)N.

Further, in a description of the embodiment, a meaning that thecomposition is low or high may be understood as a difference incomposition % of each semiconductor layer. For example, when an aluminumcomposition of a first semiconductor layer is 30% and an aluminumcomposition of a second semiconductor layer is 60%, the aluminumcomposition of the second semiconductor layer may be expressed as 30%higher than the aluminum composition of the first semiconductor layer.

A substrate 110 may be formed of a material selected from sapphire(Al₂O₃), SiC, GaAs, GaN, ZnO, Si, GaP, InP, and Ge, but is not limitedthereto. The substrate 110 may be a transparent substrate through whichlight in an ultraviolet wavelength band may be transmitted.

A buffer layer (not shown) may alleviate lattice mismatch between thesubstrate 110 and the semiconductor layers. The buffer layer may have aform of a combination of a group III element and a group V element, ormay include any one of AlN, AlGaN, InAlGaN, and AlInN. In theembodiment, the buffer layer may be AlN, but is not limited thereto. Thebuffer layer may include a dopant, but is not limited thereto.

A first conductive semiconductor layer 120 may be implemented with agroup III-V or II-VI compound semiconductor and may be doped with afirst dopant. The first conductive semiconductor layer 120 may beselected from semiconductor materials having a composition formula ofIn_(x1)Al_(y1)Ga_(1-x1-y1)N (0≤x1≤1, 0<y1≤1, and 0≤x1+y1≤1), forexample, AlGaN, AlN, InAlGaN, and the like. Further, the first dopantmay be an n-type dopant such as Si, Ge, Sn, Se, and Te. When the firstdopant is an n-type dopant, the first conductive semiconductor layer 120doped with the first dopant may be an n-type semiconductor layer.

An active layer 130 may be disposed between the first conductivesemiconductor layer 120 and a second conductive semiconductor layer 140.The active layer 130 may be a layer in which electrons (or holes)injected through the first conductive semiconductor layer 120 and holes(or electrons) injected through the second conductive semiconductorlayer 140 meet. In the active layer 130, the electrons and the holes mayrecombine and thus transition to a low energy level to generate lighthaving an ultraviolet wavelength.

The active layer 130 may have one structure among a single wellstructure, a multiple well structure, a single quantum well structure, amulti quantum well (MQW) structure, a quantum dot structure, and aquantum wire structure, and the structure of the active layer 130 is notlimited thereto.

The active layer 130 may include a plurality of well layers and aplurality of barrier layers. The well layers and the barrier layers mayhave a composition formula of In_(x2)Al_(y2)Ga_(1-x2-y2)N (0≤x2≤1,0<y2≤1, and 0≤x2+y2≤1). The aluminum composition in the well layer mayvary depending on a wavelength of light emitted from the well layer. Thewavelength of light emitted from the well layer may become shorter asthe aluminum composition becomes higher.

The second conductive semiconductor layer 140 may be formed on theactive layer 130, may be implemented with a group III-V or II-VIcompound semiconductor, and may be doped with a second dopant.

The second conductive semiconductor layer 140 may be formed ofsemiconductor materials having a composition formula ofIn_(x5)Al_(y2)Ga_(1-x5-y2)N (0≤x5≤1, 0<y2≤1, and 0≤x5+y2≤1), or amaterial selected from AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr, Ba, orthe like, the second conductive semiconductor layer 140 doped with thesecond dopant may be a p-type semiconductor layer.

An electron-blocking layer (EBL) may be disposed between the activelayer 130 and the second conductive semiconductor layer 140. Theelectron-blocking layer is a constraining layer of the active layer 130and may reduce electron separation.

The light emitting structure (120, 130, and 140) may include an etchedregion P1 in which the first conductive semiconductor layer 120 isexposed as the active layer 130 and the second conductive semiconductorlayer 140 are partially removed by mesa etching. The light emittingstructure may include an intermediate layer 160 selectively regrown onthe first conductive semiconductor layer 120 in the etched region P1.

The intermediate layer 160 may be a selectively regrown n-type ohmicsemiconductor layer. An aluminum composition of the intermediate layer160 may be smaller than that of the first conductive semiconductor layer120. For example, the aluminum composition of the intermediate layer 160may be 0% to 30% or 1% to 30%. The intermediate layer 160 may be GaN orAlGaN. According to this configuration, since an ohmic resistance of afirst electrode 170 and the intermediate layer 160 is lowered, anoperating voltage may be lowered.

The composition of the intermediate layer 160 may be the same as that ofthe first conductive semiconductor layer 120. For example, both thecompositions of the first conductive semiconductor layer 120 and theintermediate layer 160 may have a composition formula ofIn_(x1)Al_(y1)Ga_(1-x1-y1)N (0≤x1≤1, 0<y1≤1, and 0≤x1+y1≤1). In theintermediate layer 160, the first dopant (Si) may be included at aconcentration of 1E17/cm³ to 1E20/cm³.

A first insulating layer 150 may include a first hole 150 a whichexposes the first conductive semiconductor layer 120 in the etchedregion P1. That is, the first insulating layer 150 may cover a part ofthe etched region P1 and expose the remaining part of the etched regionP1 to control an area where the intermediate layer 160 is regrown. Thefirst insulating layer 150 may include at least one selected from thegroup consisting of SiO₂, Si_(x)O_(y), Si₃N₄, Si_(x)N_(y), SiO_(x)N_(y),Al₂O₃, TiO₂, AlN, and the like.

When a regrowth area is large, a regrowth rate is relatively fast, but asurface may be rough. On the other hand, when the regrowth area isnarrow, the regrowth rate is relatively slow, but the surface may besmooth. Accordingly, according to the embodiment, a regrowth layerhaving a low surface roughness while regrowth is completed in arelatively fast time may be formed by adjusting an area of the firsthole 150 a.

According to the embodiment, a ratio of the area of the etched region P1and the area of the first hole 150 a may be 1:0.3 to 1:0.7. When thearea ratio is smaller than 1:0.3 (for example, 1:0.2), since a growtharea of the intermediate layer 160 decreases, it is difficult to injectcurrent, and thus a voltage may increase. Further, when the area ratiois greater than 1:0.7 (for example, 1:0.8), there is a problem in thatthe growth area is too wide and thus surface roughness increases. Whenthe surface roughness increases, the reflectance of the first electrode170 may decrease or ohmic resistance may increase.

A thickness d1 of the intermediate layer 160 may be smaller than athickness d2 of the first insulating layer 150. The thickness of thefirst insulating layer 150 may be 10 nm to 300 nm to effectively preventmoisture penetration and contamination. Further, the intermediate layer160 may have a thickness of 10 nm to 150 nm, or 10 nm to 100 nm to lowera light absorption rate.

A ratio (d2:d1) of the thickness of the first insulating layer 150 andthe thickness of the intermediate layer 160 may be 1:0.03 to 1:0.5. Whenthe thickness ratio is less than 1:0.03, the intermediate layer 160becomes too thin to achieve sufficient ohmic contact, and when thethickness ratio is larger than 1:0.5, since the intermediate layer 160with a low aluminum composition becomes too thick, there is a problem inthat an absorption rate of the ultraviolet light increases, and thusoptical output becomes low. However, the present disclosure is notlimited thereto, and the thickness of the intermediate layer 160 may begreater than the thickness of the first insulating layer 150.

The first conductive semiconductor layer 120 may include a first subsemiconductor layer 121, a second sub semiconductor layer 122 disposedon the first sub semiconductor layer 121, a third sub semiconductorlayer 123 disposed on the second sub semiconductor layer 122, and afourth sub semiconductor layer 124 disposed on the third subsemiconductor layer 123.

An aluminum composition of the second sub semiconductor layer 122 may belower than aluminum compositions of the first sub semiconductor layer121 and the fourth sub semiconductor layer 124, and an aluminumcomposition of the third sub semiconductor layer 123 may be lower thanthe aluminum composition of the second sub semiconductor layer 122.

For example, the aluminum compositions of the first sub semiconductorlayer 121 and the fourth sub semiconductor layer 124 may be 70% to 90%,the aluminum composition of the second sub semiconductor layer 122 maybe 55% to 70%, and the aluminum composition of the third subsemiconductor layer 123 may be 45% to 65%.

The intermediate layer 160 may be disposed on the third subsemiconductor layer 123 having the lowest aluminum composition to haveimproved current injection efficiency. In this case, the aluminumcomposition of the intermediate layer 160 may be lower than the aluminumcomposition of the third sub semiconductor layer 123.

The first electrode 170 may be disposed on the intermediate layer 160.The first electrode 170 may be formed of at least one of aluminum (Al),chromium (Cr), palladium (Pd), rhodium (Rh), platinum (Pt), titanium(Ti), nickel (Ni), gold (Au), indium (In), tin (Sn), tungsten (W), andcopper (Cu).

For example, the first electrode 170 may include a first layer includingat least one of Cr, Ti, and TiN and a second layer including at leastone of Al, Rh, and Pt. However, the present disclosure is not limitedthereto, and the first electrode 170 may include various structures andmaterials to effectively block the ultraviolet light emitted to theetched region P1. According to the embodiment, since the ultravioletlight is blocked by the first electrode, there is an effect of improvinglight extraction efficiency.

Referring to FIG. 2 , the first electrode 170 may include a secondextending portion 170 a extending to an upper portion of the firstinsulating layer 150. According to this configuration, since areflection area of the first electrode 170 is widened, light extractionefficiency may be improved. A width W3 of the second extending portion170 a may be 5 μm to 15 μm. When the width W3 is less than 5 μm, theintermediate layer 160 may be partially exposed when manufacturingtolerances occur, and when the width W3 is larger than 15 μm, there is arisk of occurrence of a short circuit between the first electrode 170and a second electrode 180. The width W3 of the second extending portionmay be smaller than the width of the first electrode 170.

The etched region P1 may include a first etched region P11 disposed atan inner side based on an outer side surface 170-1 of the firstelectrode 170 and a second etched region P12 disposed at an outer sidebased on the outer side surface 170-1 of the first electrode 170. Thefirst etched region P11 is may be a region between an outer side of thelight emitting region and the outer side surface 170-1 of the firstelectrode 170, and the second etched region P12 may be a dummy regionconsidering tolerance. A ratio of an area of the first etched region P11and an area W1 of the intermediate layer 160 may be 1:0.3 to 1:0.7. Whenthe area ratio is smaller than 1:0.3 (for example, 1:0.2), since thearea of the intermediate layer 160 is small, the area which is in ohmiccontact with the first electrode 170 may decrease. Further, when thearea ratio is greater than 1:0.7 (for example, 1:0.8), since the area ofthe intermediate layer 160 may be too wide, the light absorption ratemay increase. In addition, when the growth area is too wide, sincesurface roughness increases, ohmic contact may become poor andreflectance of the first electrode 170 may decrease.

A ratio of the area of the first etched region P11 and an area W4 of thefirst electrode 170 may be 1:0.4 to 1:0.9. When the area ratio is lessthan 1:0.4, the first electrode 170 may not sufficiently cover theintermediate layer 160 and thus light extraction efficiency may bedegraded. Further, when the area ratio is greater than 1:0.9 (forexample, 1:0.95), there is a risk of occurrence of a short circuitbetween the first electrode 170 and the second electrode 180.Accordingly, the area of the first electrode may be larger than the areaof the intermediate layer.

Referring to FIG. 3 , the intermediate layer 160 may have a superlatticestructure in which a first intermediate layer 160 a and a secondintermediate layer 160 b having different aluminum compositions arestacked multiple times. The aluminum composition of the firstintermediate layer 160 a may be higher than the aluminum composition ofthe second intermediate layer 160 b. The first intermediate layer 160 aand the second intermediate layer 160 b may each have a thickness of 5nm to 10 nm, but are not limited thereto.

The first intermediate layer 160 a may satisfy a composition formula ofAl_(x)Ga_(1-x)N (0.6≤x≤1), and the second intermediate layer 160 b maysatisfy a composition formula of Al_(y)Ga_(1-y)N (0≤y≤0.5). For example,the first intermediate layer 160 a may be AlGaN and the secondintermediate layer 160 b may be GaN. However, the present disclosure isnot limited thereto, and both the first intermediate layer 160 a and thesecond intermediate layer 160 b may be AlGaN.

According to this superlattice configuration, it is possible to improveelement stability by reducing stress due to lattice mismatch whileminimizing ultraviolet light absorption.

Referring to FIG. 4 , the first insulating layer 150 may include a firstextending portion 151 extending to an upper portion of the intermediatelayer 160. According to this configuration, there is an advantage inthat the area of the intermediate layer 160 electrically connected tothe first electrode 170 may be adjusted by adjusting a width W5 of thefirst extending portion 151.

Further, according to this configuration, since a reflective electrodeis disposed on the first extending portion 151 of the first insulatinglayer 150, reflectance may be increased through an omni directionalreflector (ODR) effect.

FIG. 5 is a plan view illustrating an intermediate layer, FIG. 6 is aplan view illustrating a first electrode, and FIG. 7 is a plan view ofthe light emitting element according to one embodiment of the presentdisclosure.

Referring to FIG. 5 , a plurality of light emitting regions P2 mayextend in a first direction (an X-axis direction) and may be disposed tobe spaced apart from each other in a second direction (a Y-axisdirection) by mesa etching. The etched region P1 may be disposed tosurround the plurality of light emitting regions P2.

Since an ultraviolet semiconductor device has a relatively highprobability of light emission in a transverse magnetic mode (TM) whichemits light to the side surface compared to a semiconductor device whichemits blue light, it may be advantageous to widen a side surface of theactive layer as much as possible. Accordingly, since the light emittingregion P2 is separated into a plurality, the exposed area of the activelayer may be increased, and thus the extraction efficiency of lightemitted to the side surface may be increased. In the embodiment, a casein which the number of the plurality of light emitting regions P2 isthree is disclosed, but the number of light emitting regions P2 is notparticularly limited.

The intermediate layer 160 may include a plurality of finger portions161 disposed between the plurality of light emitting regions P2 and eachhaving a first end 161 a and a second end 161 b and an edge portion 162surrounding the plurality of light emitting regions P2. The edge portion162 may be connected to the first end 161 a and the second end 161 b ofeach of the plurality of finger portions 161. A width of each of thefinger portions 161 and the edge portion 162 may be 10 μm to 40 μm, butis not limited thereto.

Each of the plurality of light emitting regions P2 may include a firstend P21 and a second end P22, and the first end P21 of each of theplurality of light emitting regions P2 may include curved portions R1that are curved in a direction in which facing surfaces are away fromeach other. The first end 161 a of the finger portion 161 may bedisposed between the curved portions R1 of the light emitting region P2.

Since the plurality of light emitting regions P2 are curved in thedirections in which the curved portions R1 recede from each other (theY-axis direction), a width W31 of the first end P21 may become smallerthan a width W32 of the second end P22. Accordingly, in each of theplurality of finger portions 161, a width W21 of the first end 161 a maybe formed larger than a width W22 of the second end 161 b.

Referring to FIG. 6 , the first electrode 170 may be disposed on theintermediate layer 160. A shape of the first electrode 170 maycorrespond to a shape of the intermediate layer 160. The first electrode170 may include a plurality of finger electrodes 171 disposed betweenthe plurality of light emitting regions P2 and each having a first end171 a and a second end 171 b and an edge electrode 172 extending alongan edge of the first etched region P11. The edge electrode 172 may beconnected to the first end 171 a and the second end 171 b of each of theplurality of finger electrodes 171. In this case, in each of theplurality of finger electrodes 171, a width W41 of the first end 171 amay be wider than a width W42 of the second end 171 b.

The ratio of the area of the first etched region P11 and the area of theintermediate layer 160 may be 1:0.3 to 1:0.7. As described above, thefirst etched region P11 may be a region between the light emittingregion P2 and the outer side surface 170-1 of the first electrode 170.

When the area ratio is smaller than 1:0.3 (for example, 1:0.2), sincethe area of the intermediate layer 160 is small, an area which is inohmic contact with the first electrode 170 may decrease. Accordingly,the operating voltage may increase. Further, when the area ratio isgreater than 1:0.7 (for example, 1:0.8), since the area of theintermediate layer 160 is too wide, the light absorption rate mayincrease. In addition, when the growth area is too wide, since thesurface roughness increases, the ohmic contact may become poor and thereflectance of the first electrode 170 may decrease.

The ratio of the area of the first etched region P11 and the area of thefirst electrode 170 may be 1:0.4 to 1:0.9. When the area ratio is lessthan 1:0.4, the first electrode 170 may not sufficiently cover theintermediate layer 160 and thus light extraction efficiency may bedegraded. Further, when the area ratio is greater than 1:0.9 (forexample, 1:1.2), there is a risk of occurrence of a short circuit due toconnection of the first electrode 170 and the second electrode 180.

Referring to FIGS. 6 and 7 , the light emitting element according to theembodiment may include a second insulating layer 152 disposed on thefirst electrode 170 and the second electrode 180, a first pad 191disposed on the second insulating layer 152 and electrically connectedto the first electrode 170 through a first opening 152 a, and a secondpad 192 disposed on the second insulating layer 152 and electricallyconnected to the second electrode 180 through a second opening 152 b.

The second insulating layer 152 may entirely cover the first electrode170 and the second electrode 180 and expose only portions of the firstelectrode 170 and the second electrode 180. The first opening 152 awhich exposes the first electrode 170 may be formed on the first end 171a of the finger electrode 171 of the first electrode 170. As describedabove, since the first end 171 a of the finger electrode 171 of thefirst electrode 170 is formed to have a relatively great width, thefirst opening 152 a may be formed to be wide to increase a contact areabetween the first pad 191 and the first electrode 170.

The second opening 152 b of the second insulating layer 152 may bedisposed on the second electrode 180. The second electrode 180 may bedisposed on each of the plurality of light emitting regions P2 and thesecond opening 152 b may overlap each of the plurality of secondelectrodes 180.

Since the first openings 152 a are disposed between the plurality oflight emitting regions P2 and the second openings 152 b are respectivelydisposed on the plurality of light emitting regions P2, the number offirst openings 152 a may be less than the number of second openings 152b. Further, an area of the first opening 152 a may be smaller than anarea of the second opening 152 b.

The first pad 191 and the second pad 192 may extend in the seconddirection (the Y-axis direction), and may be disposed to be spaced apartfrom each other in the first direction (the X-axis direction). The firstpad 191 may be disposed to overlap the curved portions R1 and the firstends 171 a of the plurality of light emitting regions P2.

FIGS. 8A and 8B are a plan view and a cross-sectional view illustratinga state in which the light emitting region and the etched region areformed by the mesa etching, respectively, FIGS. 9A and 9B are a planview and a cross-sectional view illustrating a state in which theintermediate layer is regrown on the first conductive semiconductorlayer, respectively, FIGS. 10A and 10B are a plan view and across-sectional view illustrating a state in which the first electrodeis formed, respectively, and FIGS. 11A and 11B are a plan view and across-sectional view illustrating a state in which the second electrodeis formed, respectively.

Referring to FIGS. 8A and 8B, the plurality of light emitting regions P2may extend in the first direction and may be disposed to be spaced apartfrom each other in the second direction by mesa etching. The etchedregion P1 may be disposed to surround the plurality of light emittingregions P2. In the embodiment, the case in which the number of theplurality of light emitting regions P2 is three is disclosed, but thenumber of light emitting regions P2 is not particularly limited.

The light emitting structure on the substrate may be epitaxially grownthrough methods such as metal organic chemical vapor deposition (MOCVD),chemical vapor deposition (CVD), physical vapor deposition (PVD), atomiclayer deposition (ALD), and the like.

Referring to FIGS. 9A and 9B, in the first insulating layer 150, thefirst hole 150 a which exposes the first conductive semiconductor layer120 in the etched region P1 may be formed, and the intermediate layer160 may be regrown thereon.

When a regrowth area is large, regrowth becomes relatively fast, but asurface may be rough. On the other hand, when the regrowth area isnarrow, the regrowth becomes relatively slow, but the surface may besmooth. Accordingly, according to the embodiment, the intermediate layer160 having a low surface roughness while regrowth is completed in arelatively fast time may be formed by adjusting the area of the firsthole 150 a.

The intermediate layer 160 may be epitaxially grown through methods suchas metal organic chemical vapor deposition (MOCVD), chemical vapordeposition (CVD), physical vapor deposition (PVD), atomic layerdeposition (ALD), and the like. In this case, the dopant may be doped ata concentration of 1E17/cm³ to 1E20/cm³.

The thickness of the intermediate layer 160 may be smaller than thethickness of the first insulating layer 150. The thickness of the firstinsulating layer 150 may be 10 nm to 300 nm to effectively preventmoisture penetration or the like. Further, the intermediate layer 160may be grown to 10 nm to 150 nm to lower the light absorption rate.Accordingly, a ratio of the thickness of the first insulating layer 150and the thickness of the intermediate layer 160 may be 1:0.03 to 1:0.5.However, the present disclosure is not limited thereto, and thethickness of the intermediate layer 160 may be greater than thethickness of the first insulating layer 150.

Referring to FIGS. 10A and 10B, the first electrode 170 may be formed onthe intermediate layer 160. The first electrode 170 may be formed of atleast one of aluminum (Al), chromium (Cr), palladium (Pd), rhodium (Rh),platinum (Pt), titanium (Ti), nickel (Ni), gold (Au), indium (In), tin(Sn), tungsten (W), and copper (Cu).

For example, the first electrode 170 may include a first layer includingat least one of Cr, Ti, and TiN and a second layer including at leastone of Al, Rh, and Pt. However, the present disclosure is not limitedthereto, and the first electrode 170 may include various structures andmaterials to effectively block the ultraviolet light emitted to theetched region P1.

Referring to FIGS. 11A and 11B, the second electrode 180 may be formedon the second conductive semiconductor layer 140. The second electrode180 may include at least one of Al, Cr, Pd, Rh, Pt, Ti, Ni, and Au.However, the present disclosure is not limited thereto, and the regrownintermediate layer 160 may also be formed on the second conductivesemiconductor layer 140 like the case in which the intermediate layer160 is formed on the first conductive semiconductor layer 120. In thiscase, the intermediate layer 160 may be a P-type regrowth layer.

FIGS. 12A and 12B are graphs for describing an effect of improving anelectrical characteristic (VF enhancement) and an optical characteristic(optical output enhancement) of a short wavelength ultraviolet lightemitting diode (LED) (a peak wavelength of 265 nm) according to oneembodiment of the present disclosure. As shown in FIG. 12A, it can beseen that a short wavelength ultraviolet light emitting element with anintermediate layer has an improved electrical characteristic (VFreduction) compared to the element without the intermediate layer.

Further, as shown in FIG. 12B, in the case of a short wavelengthultraviolet light emitting element in which the intermediate layer wasselectively regrown, it can be seen that reflectance of a metalelectrode increased by forming ohmic contact without an alloy throughhigh-temperature heat treatment, and thus the optical characteristic(optical output enhancement) was improved.

FIG. 13 is a conceptual diagram of a light emitting element according toanother embodiment of the present disclosure, and FIG. 14 is a viewillustrating inclination angles of a buffer layer and a first conductivesemiconductor layer.

A substrate 210 may be formed of a material selected from sapphire(Al₂O₃), SiC, GaAs, GaN, ZnO, Si, GaP, InP, and Ge, but is not limitedthereto. The substrate 210 may be a transparent substrate through whichlight in an ultraviolet wavelength band may be transmitted.

A buffer layer 211 may alleviate lattice mismatch between the substrate210 and the semiconductor layers. The buffer layer 211 may have a formof a combination of a group III element and a group V element, or mayinclude any one of AlN, AlGaN, InAlGaN, and AlInN. In the embodiment,the buffer layer 211 may be AlN, but is not limited thereto. The bufferlayer 211 may include a dopant, but is not limited thereto.

A first conductive semiconductor layer 220 may be implemented with agroup III-V or II-VI compound semiconductor and may be doped with afirst dopant. The first conductive semiconductor layer 220 may beselected from semiconductor materials having a composition formula ofIn_(x1)Al_(y1)Ga_(1-x1-y1)N (0≤x1≤1, 0<y1≤≤1, and 0≤x1+y1≤1), forexample, AlGaN, AlN, InAlGaN, and the like. Further, the first dopantmay be an n-type dopant such as Si, Ge, Sn, Se, and Te. When the firstdopant is an n-type dopant, the first conductive semiconductor layer 120doped with the first dopant may be an n-type semiconductor layer.

An active layer 230 may be disposed between the first conductivesemiconductor layer 220 and a second conductive semiconductor layer 240.The active layer 230 may be a layer in which electrons (or holes)injected through the first conductive semiconductor layer 220 and holes(or electrons) injected through the second conductive semiconductorlayer 240 meet. In the active layer 230, the electrons and the holes mayrecombine and thus transition to a low energy level to generate lighthaving an ultraviolet wavelength.

The active layer 230 may have one structure among a single wellstructure, a multiple well structure, a single quantum well structure, amulti quantum well (MQW) structure, a quantum dot structure, and aquantum wire structure, and the structure of the active layer 230 is notlimited thereto.

The active layer 230 may include a plurality of well layers and aplurality of barrier layers. The well layers and the barrier layers mayhave a composition formula of In_(x2)Al_(y2)Ga_(1-x2-y2)N (0≤x2≤1,0<y2≤1, and 0≤x2+y2≤1). The aluminum composition in the well layer mayvary depending on a wavelength of light emitted from the well layer. Thewavelength of light emitted from the well layer may become shorter asthe aluminum composition becomes higher.

The second conductive semiconductor layer 240 may be formed on theactive layer 230, may be implemented with a group III-V or II-VIcompound semiconductor, and may be doped with a second dopant.

The second conductive semiconductor layer 240 may be formed ofsemiconductor materials having a composition formula ofIn_(x5)Al_(y2)Ga_(1-x5-y2)N (0≤x5≤1, 0<y2≤1, and 0≤x5+y2≤1), or amaterial selected from AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr, Ba, orthe like, the second conductive semiconductor layer 240 doped with thesecond dopant may be a p-type semiconductor layer.

An electron-blocking layer (EBL) may be disposed between the activelayer 230 and the second conductive semiconductor layer 240. Theelectron-blocking layer is a constraining layer of the active layer 230and may reduce electron separation.

A light emitting structure P may include an etched region P1 whichpartially exposes the first conductive semiconductor layer 220 and thebuffer layer 211. The etched region P1 may include a first etched regionW62 which exposes the first conductive semiconductor layer 220 and asecond etched region W63 which exposes the buffer layer 211. The secondetched region W63 may be formed to surround the first etched region W62.

The second etched region W63 may be formed after the first etched regionW62 is formed, but the present disclosure is not limited thereto, andthe first etched region W62 and the second etched region W63 may besimultaneously formed. Further, various semiconductor etching methodssuch as dry etching or wet etching may be used as an etching method.

A depth d61 of the first etched region W62 and a depth d62 of the secondetched region W63 may be different. The depth d62 of the second etchedregion W63 may be greater than the depth d61 of the first etched regionW62. For example, a ratio (d61:d62) of the depth d61 of the first etchedregion W62 and the depth d62 of the second etched region W63 may be 1:4to 1:9.

When the depth ratio is less than 1:4 (for example, 1:3), a portion ofthe first conductive semiconductor layer may remain and thus it maybecome vulnerable to corrosion, and when the depth ratio is greater than1:9, a process time increases and a step difference increases, and thusproductivity may decrease. Further, stability in the followingphotolithography process may decrease.

Referring to FIG. 14 , a first height d621 of a side surface of thefirst conductive semiconductor layer 220 exposed by the second etchedregion W63 may be greater than a second height d622 of a side surface ofthe buffer layer 211 exposed by the second etched region W63. When thedepth d62 of the second etched region W63 increases, since the bufferlayer 211 is etched more, the second height d622 may increase. A ratio(d621:d622) of the first height d621 and the second height d622 may be1:0.1 to 1:1.

When the height ratio is less than 1:0.1, the n-type semiconductor mayremain and thus it may become vulnerable to corrosion, and when theheight ratio is greater than 1:1, productivity may decrease due to anincrease in process time.

A first inclination angle θ2 of the side surface of the first conductivesemiconductor layer 220 exposed to the second etched region W63 may belarger than a second inclination angle θ1 of the side surface of thebuffer layer 211 exposed by the second etched region W63. This isbecause compositions of the first conductive semiconductor layer 220 andthe buffer layer 211 are different even when the same etching gas oretching solution is used. For example, the first inclination angle θ2 ofthe side surface of the first conductive semiconductor layer 220 may be40 degrees to 65 degrees. Further, the second inclination angle θ1 ofthe side surface of the buffer layer 211 exposed by the second etchedregion W63 may be 30 degrees to 60 degrees.

Referring to FIG. 13 , a first electrode 261 may be disposed on thefirst conductive semiconductor layer 220 disposed in the first etchedregion W62. The first electrode 261 may be formed of at least one ofaluminum (Al), chromium (Cr), palladium (Pd), rhodium (Rh), platinum(Pt), titanium (Ti), nickel (Ni), gold (Au), indium (In), tin (Sn),oxide (0), tungsten (W), and copper (Cu).

For example, the first electrode 261 may include a first layer includingat least one of Cr, Ti, and TiN and a second layer including at leastone of Al, Rh, and Pt. However, the present disclosure is not limitedthereto

As described in FIG. 1 , the intermediate layer (160 in FIG. 1 ) regrownfrom the first conductive semiconductor layer may be formed under thefirst electrode 261. Like the above, the intermediate layer regrown fromthe second conductive semiconductor layer may also be formed under thesecond electrode.

A first cover electrode 262 may be disposed on the first electrode 261.The first cover electrode 262 may be formed to cover the first electrode261. A material of the first cover electrode 262 may be the same as thatof the first electrode 261, but is not limited thereto. The first coverelectrode 262 may include various structures and materials toeffectively block the ultraviolet light emitted to the etched region P1.According to the embodiment, since the ultraviolet light is blocked bythe first electrode 261 or the first cover electrode 262, there is aneffect of improving light extraction efficiency.

A second electrode 271 may be disposed on the second conductivesemiconductor layer 240. The second electrode 271 may be formed of atleast one of aluminum (Al), chromium (Cr), palladium (Pd), rhodium (Rh),platinum (Pt), titanium (Ti), nickel (Ni), gold (Au), indium (In), tin(Sn), oxide (0), tungsten (W), and copper (Cu), but is not limitedthereto.

A second cover electrode 272 and a reflective electrode 273 may bedisposed on the second electrode 271. A material of each of the secondcover electrode 272 and the reflective electrode 273 may be the same asthat of the second electrode 271, but is not limited thereto. The secondcover electrode 272 may be formed to cover the second electrode 271. Thesecond electrode 271, the second cover electrode 272, and the reflectiveelectrode 273 may be made of a material which reflects light emitted tothe second conductive semiconductor layer 240. However, in a horizontalstructure, the second electrode 271 and the second cover electrode 272may be made of a material which transmits the ultraviolet light, and thereflective electrode may be omitted.

A first insulating layer 251 may be formed between the first electrode261 and the second electrode 271. The first insulating layer 251 mayinclude at least one selected from the group consisting of SiO₂,Si_(x)O_(y), Si₃N₄, Si_(x)N_(y), SiO_(x)N_(y), Al₂O₃, TiO₂, AN, and thelike. The first insulating layer 251 may be formed before the secondetched region W63 is formed, but is not limited thereto, and may beformed after the second etched region W63 is formed.

A second insulating layer 252 may be formed on the first electrode 261and the second electrode 271. A material of the second insulating layer252 may be the same as that of the first insulating layer 251. Thesecond insulating layer 252 may be thicker than the first insulatinglayer 251, but is not limited thereto. A boundary between the firstinsulating layer 251 and the second insulating layer 252 may disappearin a final product.

The second etched region W63 may include a cover region W65 in which thesecond insulating layer 252 is formed and a dummy region W64 in whichthe second insulating layer 252 is not formed. The dummy region W64 maybe a region for cutting chips. Accordingly, the dummy region W64 may ormay not be formed in the final product stage depending on a cuttingcondition.

An area of the first etched region W62 and an area of the cover regionW65 may be different. A ratio (W65:W62) of the area of the cover regionW65 and the area of the first etched region W62 may be 1:3.5 to 1:6.

When the area ratio is greater than 1:6 (for example, 1:7), since thearea of the insulating layer disposed in the second etched region W63becomes small, a problem in that the side surface of the firstconductive semiconductor layer may not be sufficiently covered mayoccur, and when the area ratio is smaller than 1:3.5, since an end ofthe insulating layer may come into contact with a cut surface or crackduring chip cutting, a defect may occur.

FIG. 15 is a cross-sectional view of the light emitting elementaccording to another embodiment of the present disclosure.

Referring to FIG. 15 , a side surface 252-1 of the second insulatinglayer 252 may be disposed in the cover region W65 of the second etchedregion W63 to surround the light emitting structure P. According to thisconfiguration, since the second insulating layer 252 entirely covers theside surface of the first conductive semiconductor layer 220, it ispossible to prevent the side surface of the first conductivesemiconductor layer 220 from being corroded.

The second insulating layer 252 may include a first opening 252 a whichexposes the first cover electrode 262 and a second opening 252 b whichexposes the second cover electrode 272. A first pad 291 may beelectrically connected to the first cover electrode 262 and the firstelectrode 261 through the first opening 252 a, and a second pad 292 maybe electrically connected to the second cover electrode 272 and thesecond electrode 271 through second opening 252 b.

This pad structure may be a flip chip structure. However, the embodimentis not limited to the flip chip structure, and a horizontal structuremay also be applied.

Referring to FIG. 16 , the side surface 252-1 of the second insulatinglayer 252 may be patterned to have a protruding shape. According to thisconfiguration, it is possible to restrain the propagation of cracksgenerated in the chip up to the active layer. When the side surface252-1 of the second insulating layer 252 is straight, the cracks mayextend to the active layer through the insulating layer. However, whenthe side surface 252-1 of the second insulating layer 252 is curved, thepropagation of the cracks may be effectively restrained.

Referring to FIGS. 17A to 17E, protrusions PT1 on the side surface ofthe second insulating layer 252 may have various curved shapes. Forexample, outwardly convex protrusions PT1 may be included as shown inFIG. 17A, and a straight portion PT2 may be disposed between theplurality of convex protrusions PT1 as shown in FIG. 17B. Widths of theprotrusions PT1 and the straight portion PT2 may be the same ordifferent. For example, the widths of the protrusions PT1 and thestraight portion PT2 may be 3 μm to 15 μm, but are not limited thereto.

Referring to FIG. 17C, the side surface of the second insulating layer252 may include concave protrusions PT3, and as shown in FIG. 17D, thestraight portion PT2 may be disposed between the plurality of concaveprotrusions PT3. Further, as shown in FIG. 17E, the side surface of thesecond insulating layer 252 may have a structure in which the convexprotrusions PT1 and the concave protrusions PT3 are mixed.

According to the above-described various embodiments of the presentdisclosure, the ultraviolet light emitting element may be designed toenable ohmic contact regardless of the aluminum composition ratio of then-type semiconductor layer.

The ultraviolet light emitting element may be applied to various typesof light source devices. For example, the light source device may be aconcept including a sterilization device, a curing device, a lightingdevice, a display device, a vehicle lamp, and the like. That is, theultraviolet light emitting element may be applied to various electronicdevices disposed in a case (body) to provide light.

The sterilization device may sterilize a desired region by including theultraviolet light emitting element according to the embodiment. Thesterilization device may be applied to household appliances such as awater purifier, an air conditioner, a refrigerator, and the like, but isnot limited thereto. That is, the sterilization device may be applied toall of various products (for example, a medical device) which requiresterilization.

For example, the water purifier may be provided with the sterilizationdevice according to the embodiment to sterilize circulating water. Thesterilization device is disposed in a nozzle or an outlet through whichthe water circulates to irradiate ultraviolet rays. In this case, thesterilization device may include a waterproof structure.

The curing device may cure various types of liquid by including theultraviolet light emitting element according to the embodiment. Theliquid may be the broadest concept including all of various materialswhich are cured when irradiated with ultraviolet rays. For example, thecuring device may cure various types of resins. Alternatively, thecuring device may be applied to cure cosmetic products such as amanicure.

The lighting device may include a light source module including asubstrate and the ultraviolet light emitting element of the embodiment,a heat dissipation part which dissipates heat from the light sourcemodule, and a power supply part which processes or converts anelectrical signal provided from the outside to provide the electricalsignal to the light source module. Further, the lighting device mayinclude a lamp, a head lamp, a street light, or the like.

The display device may include a bottom cover, a reflective plate, alight emitting module, a light guide plate, an optical sheet, a displaypanel, an image signal output circuit, and a color filter. The bottomcover, the reflective plate, the light emitting module, the light guideplate, and the optical sheet may constitute a backlight unit.

According to an embodiment, an operating voltage of an ultraviolet lightemitting element can be lowered by lowering an ohmic resistance betweena semiconductor layer and an electrode.

Further, an ultraviolet light emitting element whose optical output isimproved can be manufactured.

In addition, chip reliability can be improved by improving a problem inthat a side surface of the ultraviolet light emitting element iscorroded.

In addition, a problem that cracks are generated on the side surface ofthe ultraviolet light emitting element and propagate can be improved,and thus chip reliability can be improved. In addition, there is anadvantage of easy chip cutting.

Various useful advantages and effects of the present disclosure are notlimited to the above and can be relatively easily understood in aprocess of describing exemplary embodiments of the present disclosure.

Although the above-described embodiments are mainly described withreference to the embodiments of the present disclosure, the above isonly exemplary, and it should be understood that those skilled in theart may variously perform modifications and applications within theessential characteristics of the embodiments. For example, elementsspecifically shown in the embodiments may be modified. Further,differences related to modifications and changes should be understood asbeing included in the scope of the present disclosure defined in theappended claims.

What is claimed is:
 1. An ultraviolet light emitting element comprising: a light emitting structure including a first conductive semiconductor layer, a second conductive semiconductor layer, an active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer, and an etched region in which the first conductive semiconductor layer is exposed; a first insulating layer disposed on the light emitting structure and including a first hole which exposes a portion of the etched region; a first electrode electrically connected to the first conductive semiconductor layer; and a second electrode electrically connected to the second conductive semiconductor layer, wherein the light emitting structure includes an intermediate layer disposed on the first conductive semiconductor layer exposed in the first hole, the first electrode is disposed on the intermediate layer, wherein the first conductive semiconductor layer includes: a first sub semiconductor layer, a second sub semiconductor layer disposed on the first sub semiconductor layer, a third sub semiconductor layer disposed on the second sub semiconductor layer, and a fourth sub semiconductor layer disposed on the third sub semiconductor layer; wherein an aluminum composition of the second sub semiconductor layer is lower than aluminum compositions of the first sub semiconductor layer and the fourth sub semiconductor layer; wherein an aluminum composition of the third sub semiconductor layer is lower than the aluminum composition of the second sub semiconductor layer; and wherein the intermediate layer is disposed on the third sub semiconductor layer.
 2. The ultraviolet light emitting element of claim 1, wherein a thickness of the intermediate layer is smaller than a thickness of the first insulating layer.
 3. The ultraviolet light emitting element of claim 2, wherein a ratio of the thickness of the first insulating layer and the thickness of the intermediate layer is 1:0.03 to 1:0.5.
 4. The ultraviolet light emitting element of claim 1, wherein the first insulating layer includes a first extending portion extending to an upper portion of the intermediate layer.
 5. The ultraviolet light emitting element of claim 1, wherein: the first electrode includes a second extending portion extending to an upper portion of the first insulating layer; and a width of the second extending portion is 5 μm to 15 μm.
 6. The ultraviolet light emitting element of claim 1, wherein: first intermediate layers and second intermediate layers having different aluminum compositions are stacked multiple times in the intermediate layer; and the aluminum composition of each of the first intermediate layers is higher than the aluminum composition of each of the second intermediate layers.
 7. The ultraviolet light emitting element of claim 1, wherein an aluminum composition of the intermediate layer is lower than the aluminum composition of the third sub semiconductor layer.
 8. The ultraviolet light emitting element of claim 1, wherein: the light emitting structure includes a plurality of light emitting regions extending in a first direction and spaced apart from each other in a second direction perpendicular to the first direction; the intermediate layer includes a plurality of finger portions disposed between the plurality of light emitting regions and each having a first end and a second end, and an edge portion surrounding the plurality of light emitting regions; and the edge portion is connected to the first ends and the second ends of the plurality of finger portions.
 9. The ultraviolet light emitting element of claim 8, wherein a width of the first end is greater than a width of the second end in each of the plurality of finger portions.
 10. The ultraviolet light emitting element of claim 9, wherein: the first electrode includes a plurality of finger electrodes disposed between the plurality of light emitting regions and each having a first end and a second end, and an edge electrode surrounding the plurality of light emitting regions; the edge electrode is connected to the first ends and the second ends of the plurality of finger electrodes; and a width of the first end is greater than a width of the second end in each of the plurality of finger electrodes.
 11. The ultraviolet light emitting element of claim 10, comprising: a second insulating layer disposed on the first electrode and the second electrode, and including a first opening which exposes the first electrode and a second opening which exposes the second electrode; a first pad disposed on the second insulating layer and electrically connected to the first electrode through the first opening; and a second pad disposed on the second insulating layer and electrically connected to the second electrode through the second opening.
 12. The ultraviolet light emitting element of claim 11, wherein: the first opening is disposed on the first end of the finger portion; and the second opening is disposed on the second electrode.
 13. The ultraviolet light emitting element of claim 12, wherein: each of the plurality of light emitting regions includes a first end and a second end; the first end of each of the plurality of light emitting regions includes curved portions curved in directions receding from each other; and the first pad overlaps the curved portions of the plurality of light emitting regions.
 14. The ultraviolet light emitting element of claim 1, wherein the intermediate layer is regrown on the first conductive semiconductor layer.
 15. The ultraviolet light emitting element of claim 1, wherein and an aluminum composition of the intermediate layer is lower than an aluminum composition of the first conductive semiconductor layer. 